Pivot devices may include at least two parts that are configured for rotation of one part relative to the other. For example, the pivot device may be in the form of a hinge in which a torque is required to rotate a sleeve and a shaft with respect to one another.
Asymmetric friction torque may be desired in certain applications to maintain the overall assembly comprising the pivot device in a closed position and to resist movement to an open position, for example, but would allow a user to close the assembly from an open position with greater ease. For example, pivot devices may be incorporated in many applications that utilize a clam-shell design, such as a mobile phone or laptop, wherein it is generally desired to provide resistance to opening the lid relative to the base that is greater than the resistance to closing the lid relative to the base, or vice versa. Other examples of applications for such pivot devices may be a drive mechanism or a locking mechanism in which asymmetric friction torque is desired during displacement of various parts of the mechanism between two different positions, such as the movement of a latch or pawl from a locked to an unlocked position.
The configurations needed to generate the asymmetric friction torque for such pivot devices may be complex or require multiple parts. There is therefore a need for improved pivot devices in terms of at least one of cost, manufacturability, the elimination of the need for one or more components or other elements such as lubrication, and performance.